JP5969846B2 - Polishing pad and method for forming the same - Google Patents

Description

  The present invention relates to a polishing pad having a surface on one side of an elastic resin sheet as a polishing surface, and a method for forming the same.

  Bare silicon, semiconductor devices, magnetic disk substrates, and the like are polished to smooth their surfaces. Such polishing is a process in which a polishing pad (slurry) in which abrasive grains are dispersed in an alkaline solution or the like is supplied to a surface to be polished and a polishing pad is pressed against the surface to be polished and rotated. This is called polishing (CMP).

  The polishing pad is made of various materials according to the required smoothness. In particular, in a polishing pad for final finishing, an elastic resin sheet made of an elastic material such as urethane resin formed by a wet film forming method is often used. The wet film forming method is a method in which a resin solution in which a resin is dissolved is applied to one surface of a film forming substrate, and the applied resin solution is coagulated by immersing it in a coagulating liquid bath. . By replacing the solvent and the coagulation liquid in the resin solution, the resin in the resin solution is aggregated and regenerated (coagulated) to form an elastic resin sheet.

  A plurality of elongated bubbles extending from one surface of the elastic resin sheet to the other surface are formed inside the elastic resin sheet formed by the wet film forming method (Patent Document 1 below). The bubbles are formed in a process in which the resin is aggregated by a wet film forming method, and function as a space for temporarily storing the slurry when performing polishing.

  For example, when the object to be polished is pressed against a part of the rotating polishing pad, the bubbles in the part contract, and the slurry stored inside is discharged toward the object to be polished. When the object to be polished moves to another part, the bubbles expand and return to the original size, and the slurry is stored in the process in the process. As described above, the bubbles repeatedly discharge and store the slurry (hereinafter, such an operation may be referred to as “pumping”), so that a predetermined amount is always provided between the polishing surface of the polishing pad and the object to be polished. The slurry is circulated and fed. As a result, clogging of the polishing pad is prevented, the polishing rate is improved, and polishing with excellent surface quality can be performed.

  The present inventors have found that when the elongated bubbles in the elastic resin sheet are not formed substantially perpendicular to the polishing surface but formed so as to be inclined with respect to the polishing surface, the pumping effect is further improved. I found it. The reason is presumed as follows.

  The elongated bubbles have an opening at the tip on the polishing surface side, and the slurry is discharged and stored through the opening. If the bubbles are inclined with respect to the polishing surface, the opening is not yet blocked by the object to be polished when the object to be polished is pressed and the bubbles start to contract. That is, there is a time difference between the timing when the bubble starts to contract and the timing when the opening at the tip of the bubble is blocked. As a result, since the slurry is discharged more smoothly than in the past, the circulation of the slurry is promoted, and the pumping effect is improved.

  As a method for forming slender bubbles so as to be inclined with respect to the polishing surface, a resin is used in a solidification step of a wet film formation method (step of solidifying a resin solution in which a resin is dissolved in a coagulation liquid). There is a method in which the film formation substrate coated with the solution is slowly lowered and immersed while maintaining a state perpendicular to the liquid surface of the coagulation liquid. In this case, the bubbles are formed such that the tip on the opposite side (polishing surface side) from the film forming substrate is inclined toward the coagulating liquid side (downward).

JP 2005-335028 A

  All the bubbles formed by the above method are formed so as to be inclined in the same direction. For this reason, when a polishing pad having a circular top view is created using an elastic resin sheet formed by such a method, the angle formed between the inclination direction of the bubble and the circumferential direction at the position of the bubble is determined for each bubble. It will be different.

  That is, when polishing is performed by rotating the polishing pad, there is a bubble that closes the opening after the object to be polished is pressed and shrinks, but shrinks after the opening is closed first. There are also such bubbles. As a result, the pumping effect is different for each bubble, and the amount of the slurry to be circulated locally increases or decreases on the polishing surface of the polishing pad. For this reason, polishing unevenness may occur.

  The present invention has been made in view of such a problem, and the object thereof is polishing capable of suppressing the occurrence of polishing unevenness because the function of storing and discharging slurry is substantially uniformly exhibited in each bubble. It is to provide a pad and a method of forming the pad.

In order to solve the above problems, the polishing pad according to the present invention is a polishing pad having a polishing surface as a surface on one side of an elastic resin sheet that is circular in plan view, and a supported surface as a surface on the other side, A plurality of elongated bubbles extending from the supported surface toward the polishing surface are formed inside the elastic resin sheet, and each of the bubbles has a large diameter portion and the large diameter portion toward the polishing surface. At least in the vicinity of the polishing surface, and an elongated portion extending so as to be inclined with respect to the polishing surface, and when viewed along a direction perpendicular to the polishing surface, the inclined portion is When the angle formed between the extending direction and the circumferential direction of the elastic resin sheet at the position of the inclined portion is defined as a first angle, all the bubbles are set to be substantially the same as each other. Formed It is characterized by a door.

  The polishing pad according to the present invention has an elastic resin sheet, and a plurality of elongated bubbles extending from the supported surface toward the polishing surface are formed inside the elastic resin sheet. Each bubble has an inclined portion formed so as to be inclined with respect to the polishing surface at least in the vicinity of the polishing surface. Since such bubbles are formed, the slurry is stored and discharged in each bubble when polishing is performed, and the circulation supply of the slurry to the surface to be polished is promoted.

  In the present invention, when the elastic resin sheet is viewed along a direction perpendicular to the polishing surface, a direction in which the inclined portion of the bubble extends and a circumferential direction of the elastic resin sheet at the position of the inclined portion are formed. When the angle is the first angle, all the bubbles are formed so that the first angles are substantially the same.

  In other words, the angle formed between the inclination direction of the bubbles extending toward the polishing surface and the direction in which the bubbles advance with respect to the object to be polished when polishing is performed is substantially the same for all the bubbles. Is formed. For this reason, the time difference between the timing when the object to be polished is pressed and the bubbles contract and the timing when the opening of the bubbles is blocked by the object to be polished is substantially the same for all the bubbles. As a result, since the function of storing and discharging the slurry is exhibited substantially uniformly in each bubble, the occurrence of uneven polishing can be suppressed.

  In order to solve the above-described problems, a polishing pad forming method according to the present invention is a polishing pad having a polishing surface on one side and a supported surface on the other side of a circular elastic resin sheet in plan view. A preparation method comprising preparing a resin solution in which a resin is dissolved, and applying the resin solution to one surface of a film-forming substrate that is circular in plan view, A coating step for forming, and a solidifying step for bringing the solidified liquid into contact with the surface of the layer to be solidified to solidify the layer to be solidified. The position in contact with the coagulation liquid moves along the radial direction or the circumferential direction of the layer to be coagulated with the passage of time.

  The method for forming a polishing pad according to the present invention includes a preparation process, an application process, and a coagulation process. The preparation step is a step of preparing a resin solution in which a resin is dissolved. The application step is a step of forming a solidified layer by applying the resin solution to one surface of a film forming substrate that is circular in plan view. The layer to be solidified is a portion that later becomes an elastic resin sheet. The solidification step is a step in which a solidified liquid is brought into contact with the surface of the layer to be solidified to solidify the layer to be solidified to form an elastic resin sheet.

  When the layer to be coagulated comes into contact with the coagulating liquid, the solvent of the layer to be coagulated is discharged toward the coagulating liquid, and the resin is aggregated and regenerated in the portion. As a result, in the inside of the layer to be solidified, bubbles having a shape inclined toward the contact portion with the coagulating liquid are formed.

  In the coagulation step, the layer to be coagulated and the coagulation liquid are arranged so that the position in contact with the coagulation liquid on the surface of the layer to be coagulated moves along the radial direction or the circumferential direction of the layer to be coagulated with time. Contact is made. For this reason, the shape of the bubbles formed inside the elastic resin sheet is inclined along the radial direction or the circumferential direction of the elastic resin sheet. That is, the first angles in all the bubbles formed on the elastic resin sheet are substantially the same.

  As a result, in the polishing pad obtained by the forming method according to the present invention, the time difference between the timing at which the object to be polished is pressed and the bubbles contract and the timing at which the opening of the bubbles is blocked by the object to be polished is all The bubbles are substantially the same. Thereby, since the function of storing and discharging the slurry is exhibited substantially uniformly in each bubble, the occurrence of uneven polishing can be suppressed.

  In the method for forming a polishing pad according to the present invention, in the solidification step, it is preferable that the solidification liquid is brought into contact with a part of the surface of the layer to be solidified while rotating the film-forming substrate.

  In this preferred embodiment, in the coagulation step, the coagulation liquid is brought into contact with a part of the surface of the layer to be coagulated while rotating the film forming substrate. For this reason, the position in contact with the coagulating liquid on the surface of the layer to be coagulated moves along the circumferential direction of the elastic resin sheet with the passage of time. As a result, it is possible to easily form an elastic resin sheet in which the first angles of all the formed bubbles are substantially the same.

  In the method for forming a polishing pad according to the present invention, in the solidification step, the film formation is performed so that the solidified layer faces the liquid surface of the solidified liquid and a central portion of the solidified layer protrudes. It is also preferred that the layer to be solidified is immersed in the coagulating liquid from the central portion with the base material deformed.

  In this preferred embodiment, in the coagulation step, the layer to be solidified is made to face the liquid surface of the coagulation liquid, and the film forming substrate is deformed so that the central portion of the layer to be coagulated protrudes. That is, after the film-forming substrate is arranged so that the layer to be solidified faces the liquid surface of the coagulating liquid, the central portion of the layer to be solidified protrudes toward the coagulating liquid.

  In this state, the layer to be solidified is immersed from the central portion (projected) into the solidified liquid. For this reason, the position in contact with the coagulating liquid on the surface of the layer to be coagulated moves while expanding in a circular shape from the center of the elastic resin sheet toward the outer peripheral portion. That is, it moves along the radial direction of the elastic resin sheet with the passage of time. As a result, it is possible to easily form an elastic resin sheet in which the first angles of all the formed bubbles are substantially the same.

  ADVANTAGE OF THE INVENTION According to this invention, the function to store and discharge | emit a slurry is exhibited substantially uniformly in each bubble, and the polishing pad which can suppress generation | occurrence | production of a polishing nonuniformity, and its formation method can be provided.

It is sectional drawing which shows a part of polishing pad which concerns on 1st embodiment of this invention. It is a figure which shows arrangement | positioning of the bubble formed in the elastic resin sheet of the polishing pad shown in FIG. FIG. 2 is a process diagram schematically showing a manufacturing process of the polishing pad shown in FIG. 1. It is a schematic diagram for demonstrating a coagulation | solidification process among the processes shown in FIG. It is a figure which shows arrangement | positioning of the bubble formed in the elastic resin sheet of the polishing pad which concerns on 2nd embodiment of this invention. It is a schematic diagram for demonstrating a solidification process among the manufacturing processes of the polishing pad shown in FIG. It is a schematic diagram for demonstrating a solidification process among the manufacturing processes of the polishing pad shown in FIG. It is a figure which shows arrangement | positioning of the bubble formed in the elastic resin sheet of the polishing pad which concerns on the comparative example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  First, the configuration of the polishing pad 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing a part of the polishing pad 1, and FIG. 2 is a view showing the arrangement of bubbles 10 formed in the elastic resin sheet 2 of the polishing pad. As shown in FIGS. 1 and 2, the polishing pad 1 has an elastic resin sheet 2 that is circular in plan view.

  One surface of the elastic resin sheet 2 is a polishing surface Sp for polishing an object to be polished. The other surface of the elastic resin sheet 2 is a supported surface Sf for attaching the polishing pad 1 to the polishing apparatus. In the present embodiment, the pad base material 20 is bonded to the supported surface Sf. The pad base material 20 is formed of a sheet-like polyethylene terephthalate (hereinafter referred to as PET) that is circular in plan view.

  A double-sided tape 30 is affixed to the opposite side of the surface of the pad base material 20 that contacts the supported surface Sf. After the release paper (not shown) of the double-sided tape 30 is removed, the polishing pad 1 is attached to the polishing apparatus by sticking the double-sided tape 30 on the polishing surface plate of the polishing apparatus.

  The material of the elastic resin sheet 2 is preferably a polyurethane resin formed by a so-called wet film forming method from the viewpoint of more effectively and reliably achieving the object of the invention, but if it is an elastic material that is hydrophobic and soluble in a polar solvent, There is no particular limitation.

  Innumerable bubbles are formed inside the elastic resin sheet 2. The bubbles are formed in various sizes, and are in a state of communicating in a mesh shape. In the following description, among these bubbles, they are elongated bubbles formed so as to extend from the supported surface Sf toward the polishing surface Sp, and are formed so as to cover substantially the entire thickness of the elastic resin sheet 2. Focusing only on relatively large bubbles, these will be expressed as “bubble 10” in particular. A large number of such bubbles 10 are formed inside the elastic resin sheet 2, but for convenience of illustration and description, only a part of them is drawn in FIGS. 1 and 2.

  As shown in FIG. 1, each of the bubbles 10 includes a large-diameter portion 11 formed at a relatively large diameter in the pad base material 20 side (supported surface Sf side), and a polishing surface from the large-diameter portion 11. And an inclined portion 12 extending elongated toward Sp. The extending direction of the inclined portion 12 is not perpendicular to the polishing surface Sp, but is inclined to the polishing surface Sp.

  The bubble 10 has an opening 13 formed at the tip on the polishing surface Sp side. On the other hand, no opening is formed at the tip on the supported surface Sf side (in addition, since a minute bubble exists between the bubble 10 and the supported surface Sf, the bubble is passed through these minute bubbles. 10 may communicate with the supported surface Sf side).

  Since the bubble 10 has such a shape, when polishing with the polishing pad 1, it functions as a pump for circulating and supplying slurry between the polishing surface Sp and the object to be polished. Demonstrate. That is, when an object to be polished is pressed against a part of the polishing surface Sp of the rotating polishing pad 1, the elastic resin sheet 2 is deformed to cause the bubbles 10 in the part to contract and the slurry stored inside. Is discharged toward the object to be polished. Further, when the object to be polished moves (relatively) to another part, the bubbles 10 expand and return to the original size, and in the process, the slurry is stored inside. As described above, the bubbles 10 repeatedly discharge and store the slurry (pumping is performed), whereby a predetermined amount of slurry is always circulated and supplied between the polishing surface Sp of the polishing pad 1 and the object to be polished. As a result, clogging of the polishing pad 1 is prevented, the polishing rate is improved, and polishing with excellent surface quality is performed.

  As shown in FIG. 2, when the elastic resin sheet 2 is viewed along a direction perpendicular to the polishing surface Sp, the direction in which each inclined portion 12 extends toward the polishing surface Sp (in FIG. 2, indicated by an arrow AR1). The angle (first angle) formed between the direction indicated) and the circumferential direction of the elastic resin sheet 2 at the position of the inclined portion 12 (the direction indicated by the arrow AR2 in FIG. 2) is all about 180 degrees. . The circumferential direction of the elastic resin sheet 2 is a direction in which the elastic resin sheet 2 that forms a circle in plan view rotates along the circumference. In the present embodiment, it can also be said that the elastic resin sheet 2 rotates relative to the object to be polished. In FIG. 2, the clockwise direction is the circumferential direction with the center of the elastic resin sheet 2 that is circular in a top view as the rotation axis.

  The polishing pad 1 according to this embodiment has the following effects because the first angle is substantially the same (about 180 degrees) for all the bubbles 10. When the elastic resin sheet 2 rotates relative to the object to be polished, the object to be polished approaches the bubble 10 from the large diameter portion 11 side. That is, the object to be polished moves relatively in the direction opposite to the arrow AR2, and approaches the bubble 10.

  Since the elastic resin sheet 2 is deformed when the object to be polished is pressed, when the object to be polished approaches as described above, the large-diameter portion 11 of the bubbles 10 is first compressed and its volume decreases. At this time, the opening 13 of the bubble 10 has not been blocked by the object to be polished. Therefore, the slurry stored in the bubbles 10 is smoothly discharged through the opening 13 and supplied between the polishing surface Sp and the object to be polished.

  Thereafter, the object to be polished further moves relative to close the opening 13. Immediately thereafter, the opening 13 is opened by the relative movement of the object to be polished, and the bubble 10 returns to its original size. At that time, the slurry existing between the polishing surface Sp and the object to be polished is sucked and stored again in the bubbles 10.

  As described above, since there is a time difference between the timing at which the volume of the bubble 10 starts to decrease and the timing at which the opening 13 is blocked, the slurry is smoothly discharged and stored. The time difference is caused by the inclined portion 12 of the bubble 10 being inclined with respect to the polishing surface Sp.

  Furthermore, in this embodiment, since the first angle is substantially the same (about 180 degrees) for all the bubbles 10, the time difference is also substantially the same for all the bubbles 10. As a result, the function of storing and discharging the slurry is exhibited substantially uniformly in each of the bubbles 10, so that occurrence of polishing unevenness can be suppressed.

  As a method of arranging the bubbles 10 as shown in FIG. 2, for example, a plurality of elastic resin sheets 2 in which the bubbles 10 are formed so that the inclination direction of the inclined portion 12 is a constant direction are prepared, and A method of arranging them in a sector shape is also conceivable. However, in this case, since a plurality of elastic resin sheets 2 need to be bonded together, the manufacturing process becomes complicated. Furthermore, in the boundary part of the some elastic resin sheet 2, when the slurry approachs into the inside of the polishing pad 1 from the boundary part, the adhesive force of the double-sided tape is reduced, and the elastic resin sheet 2 is peeled off at the part. There is a possibility.

  On the other hand, in the present embodiment, the elastic resin sheet 2 having a circular shape in a top view is integrally formed as a single sheet, so that the manufacturing process is relatively simple, and the elastic resin sheet 2 is peeled off at the boundary portion. There is no possibility of doing so.

  Next, the manufacturing process of the polishing pad 1 will be described with reference to FIGS. FIG. 3 is a process diagram showing an outline of the manufacturing process of the polishing pad 1, and FIG. 4 is a schematic diagram for explaining the solidification process among the manufacturing processes. Hereinafter, description will be made in the order of steps shown in FIG.

  First, the preparation step (S1) is a step of preparing a resin solution in which a polyurethane resin is dissolved. Specifically, the polyurethane resin is dissolved by mixing a polyurethane resin, a water-miscible organic solvent capable of dissolving the polyurethane resin, and an additive.

  As the organic solvent, N, N-dimethylformamide (hereinafter abbreviated as DMF) was used. The polyurethane resin is selected from polyurethane resins such as polyester, polyether and polycarbonate.

  In view of the formation of relatively large bubbles 10 inside the elastic resin sheet 2, the resin solution is obtained by dissolving 20% by weight of polyurethane resin in DMF, and the viscosity is determined using a B-type rotational viscometer. When measured at 25 ° C., it is desirable that the range be 3 to 10 Pa · s, preferably 3 to 6 Pa · s.

  The additive is added to control the size and number of bubbles 10 formed in the elastic resin sheet 2, and a pigment such as carbon black, a hydrophilic additive, a hydrophobic additive, or the like is used. Can do.

  The resin solution obtained as described above contains a large number of bubbles immediately after mixing. Therefore, it is desirable to perform vacuum defoaming before performing the next coating step.

  The subsequent application step (S2) is a step of applying the resin solution obtained in the preparation step to one surface of the film forming substrate 40 to form the solidified layer 15. The coagulated layer 15 is a portion that will later become the elastic resin sheet 2. The film forming substrate 40 is a base for forming the elastic resin sheet 2 by a wet film forming method, and in this embodiment, a PET film having a circular shape in plan view is used. The shape of the film forming substrate 40 in plan view is the same as the shape of the pad substrate 20.

  In the coating step, the resin solution is coated substantially uniformly on the film forming substrate 40 by a coating device such as a knife coater. In the present embodiment, the knife coater was adjusted so that the coating thickness of the resin solution (the thickness of the solidified layer 15) was in the range of 0.8 to 1.2 mm.

  The subsequent solidification step (S3) is a step of forming the elastic resin sheet 2 by bringing the solidified liquid LQ into contact with the surface of the solidified layer 15 formed in the coating step and solidifying the solidified layer 15. The coagulation liquid LQ is a liquid that is a poorer solvent for the polyurethane resin than the solvent (DMF) in the resin solution, and water is used in this embodiment. In order to adjust the coagulation rate (regeneration rate) of the polyurethane resin, a solution obtained by adding an organic solvent such as DMF to water may be used as the coagulation liquid LQ. The temperature of the coagulation liquid LQ was controlled to be 15 to 20 ° C.

  When the solidified liquid LQ is brought into contact with the surface of the solidified layer 15 (resin solution), DMF at the interface between the solidified layer 15 and the solidified liquid LQ diffuses toward the solidified liquid LQ, and the resin in the portion is regenerated. As a result, a film is formed. As a result, a skin layer having a microporous structure in which many fine bubbles are formed is formed in the range of several μm in thickness from the surface of the layer to be solidified 15.

  Thereafter, DMF diffuses relatively slowly through the skin layer from the layer to be solidified 15 toward the solidified liquid LQ, and at the same time, the solidified liquid LQ permeates into the layer to be solidified 15 through the skin layer. That is, DMF and water are replaced. Accordingly, in the solidified layer 15, resin aggregation and regeneration proceed from the vicinity of the skin layer toward the film forming substrate 40 side. The aggregation speed (regeneration speed) is fast near the skin layer, and slows away from the skin layer.

  As the resin agglomerates, bubbles filled with the coagulating liquid LQ are formed inside the layer 15 to be coagulated, but as a result of the aggregation proceeding as described above, the bubbles are formed from the film forming substrate 40 side. It is formed to be elongated so as to extend toward the skin layer side. Further, due to the difference in the aggregation rate, the bubbles have a large diameter on the film forming substrate 40 side and are elongated near the skin layer. Through the above process, the elongated bubbles 10 having the large diameter part 11 and the inclined part 12 as described with reference to FIG. 1 are formed.

  The solidification process will be described more specifically with reference to FIG. FIG. 4 schematically shows a state during the solidification process. As shown in FIG. 4, the film forming substrate 40 having the solidified layer 15 formed on one surface side is held by a holding device (not shown) in a state where the normal direction of the surface is horizontal. Yes. The holding device has a rotation mechanism, and the film-forming substrate 40 rotates at a constant speed along the circumference of the surface on which the layer to be solidified 15 is formed (in the direction indicated by the arrow AR3). .

  In this state, the coagulating liquid LQ is discharged from the coagulating liquid supply apparatus 50, and the discharged coagulating liquid LQ is brought into contact with the surface of the solidified layer 15. The coagulating liquid supply apparatus 50 is a container in which a slit 51 having a length substantially the same as the radius of the film forming substrate 40 is formed, and an apparatus for discharging the coagulating liquid LQ stored inside from the slit 51 to the outside. It is. The coagulating liquid supply apparatus 50 includes a pressurizing apparatus (not shown), and the amount of coagulating liquid LQ discharged from the slit 51 (discharge amount per unit time) is controlled by the pressurizing apparatus.

  As shown in FIG. 4, the coagulating liquid supply apparatus 50 is configured so that one end of the slit 51 is disposed at the center position of the film forming substrate 40 and the other end is disposed at the outer peripheral end of the film forming substrate 40. In this state, 51 is brought close to the surface of the layer 15 to be solidified. In this state, the coagulation liquid LQ is discharged from the slit 51. The amount of the coagulating liquid LQ discharged per unit time is such that the entire portion of the surface of the layer to be coagulated 15 facing the slit 51 is always in contact with the coagulating liquid LQ. Amount.

  The coagulating liquid supply device 50 is stationary, and the film forming substrate 40 (coagulated layer 15) is rotated as described above. For this reason, the position of the surface of the layer to be solidified 15 that is in contact with the coagulating liquid LQ moves along the circumferential direction (direction opposite to the arrow AR3) of the layer to be solidified 15 with the passage of time.

  Of the surface of the layer 15 to be solidified, the portion near and above the slit 51 in FIG. 4 is a portion that will come into contact with the coagulating liquid LQ as the film forming substrate 40 rotates. In this portion, resin aggregation starts to proceed toward the contact portion with the coagulation liquid LQ, that is, downward, and thereafter contact with the coagulation liquid LQ. As a result, in the portion of the solidified layer 15 that has passed through the slit 51, the bubbles 10 are formed so as to extend from the film forming substrate 40 side toward the surface of the solidified layer 15. In addition, each of the bubbles 10 is in a state where the surface side portion is inclined along the rotation direction (arrow AR3) of the film forming substrate 40. That is, the inclined portion 12 as described with reference to FIGS. 1 and 2 is formed.

  After the discharge of the coagulation liquid LQ from the slit 51 is started, when the rotation angle of the film formation substrate 40 becomes 360 degrees or more and the skin layer is formed on the entire surface of the layer to be solidified, the film formation substrate 40 is formed. And the discharge of the coagulating liquid LQ from the slit 51 are stopped. At this time, the bubbles 10 as described above are formed in the entire solidified layer 15 and are in the state shown in FIG. At this time, from the viewpoint of preventing the coagulation liquid from dripping, a thickener (water-soluble polysaccharide, starch, carboxymethyl cellulose, alginic acid, etc.) may be added to the coagulation liquid.

  The subsequent washing / drying step (S4) is a step in which the elastic resin sheet 2 formed by the coagulation step is washed to remove DMF and then dried. The cleaning is performed by preparing a cleaning tank in which a cleaning liquid (water) is stored and immersing the entire elastic resin sheet 2 and the film forming substrate 40 in the cleaning liquid a plurality of times. Drying is performed using a dryer that is heated and dried with hot air.

  In the subsequent grinding process (S5), the surface side of the elastic resin sheet 2 (the side opposite to the film forming substrate 40) is ground to remove irregularities on the surface of the skin layer to form a flat polished surface Sp. It is a process. By this grinding process, the thickness variation of the elastic resin sheet 2 is eliminated, and at the same time, an opening 13 is formed at the tip of each bubble 10.

  In the subsequent bonding step (S6), after removing the film formation substrate 40 from the elastic resin sheet 2, an adhesive is applied to the supported surface Sf of the elastic resin sheet 2 (the surface in contact with the film formation substrate 40). It is the process of bonding the pad base material 20 through. A double-sided tape 30 from which one release paper is removed is attached to the surface of the pad base 20 opposite to the elastic resin sheet 2. As already described, the double-sided tape 30 is for attaching the polishing pad 1 to the polishing apparatus.

  Next, the configuration of the polishing pad 1a according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram showing the arrangement of the bubbles 10a formed on the elastic resin sheet 2a of the polishing pad 1a. As shown in FIG. 5, the polishing pad 1a is different from the polishing pad 1 only in the arrangement of the bubbles 10a formed in the elastic resin sheet 2a, and is the same as the polishing pad 1 in the other respects. In the following description, only the difference will be described, and detailed description of points common to the polishing pad 1 will be omitted. In the following description, a portion of the polishing pad 1a corresponding to the configuration of the polishing pad 1 (for example, the pad base material 20) is described with a letter “a” such as “pad base material 20a”.

  Each of the bubbles 10a includes a large diameter portion 11a formed with a relatively large diameter at the pad base material 20a side (supported surface Sfa side), and an inclined portion 12a elongated from the large diameter portion 11a toward the polishing surface Spa. And have. The direction in which the inclined portion 12a extends is not perpendicular to the polishing surface Spa, but is inclined to the polishing surface Spa. This is the same as the bubble 10 of the polishing pad 1.

  On the other hand, as shown in FIG. 5, when the elastic resin sheet 2a is viewed along a direction perpendicular to the polishing surface Spa, the respective inclined portions 12a extend in the direction toward the polishing surface Spa (in FIG. 5, arrows The angle (first angle) formed by the direction indicated by AR4) and the circumferential direction of the elastic resin sheet 2a at the position of the inclined portion 12a (the direction indicated by the arrow AR5 in FIG. 5) is about 90 degrees. ing. This is different from the polishing pad 1 in which the first angles are all 180 degrees.

  In the polishing pad 1a according to the present embodiment, the first angle is substantially the same (about 90 degrees) for all the bubbles 10a. As a result, the function of the bubbles 10a storing and discharging the slurry (for the same reason as that of the polishing pad 1) is exerted substantially uniformly in each of the bubbles 10a, so that it is possible to suppress the occurrence of polishing unevenness. It has become.

  Furthermore, in this embodiment, as shown in FIG. 5, all the inclined portions 12a are inclined so as to extend toward the center of the polishing surface Spa. For this reason, the slurry discharged from the opening 13a is directed toward the center of the polishing surface Spa. As a result, the retention performance of the slurry between the object to be polished and the polishing surface Spa can be improved.

  Then, the manufacturing process of the polishing pad 1a is demonstrated. The polishing pad 1a is manufactured through substantially the same process as the manufacturing process of the polishing pad 1 shown in FIG. 3, but the manufacturing process is different from the manufacturing process of the polishing pad 1 only in the solidification process. Hereinafter, only the solidification step of the manufacturing process of the polishing pad 1a will be described, and the other steps are the same as those already described, and thus description thereof will be omitted.

  This will be described with reference to FIGS. These are schematic diagrams for explaining the solidification step in the manufacturing process of the polishing pad 1a. First, as shown in FIG. 6A, a film forming substrate 40a having a solidified layer 15a formed on one surface and a stamping die 60 are prepared. The pressing die 60 is a disk-like member having the same shape as the film forming substrate 40a when viewed from above, and a surface 61 on one side thereof protrudes so as to form a part of a spherical surface. The stamping die 60 may be any material that is harder than the film forming substrate 40a, and for example, a metallic one can be used.

  Thereafter, as shown in FIG. 6B, the surface 61 of the pressing die 60 is pressed against the surface of the film forming substrate 40a on which the solidified layer 15a is not formed (hereinafter referred to as the back surface 41a). Then, the film forming substrate 40a is deformed into a spherical shape. At this time, substantially the entire back surface 41a is in contact with the surface 61, and the pressing die 60 and the film forming substrate 40a are fixed by a fixing jig (not shown) in this state. As a result, the layer 15a to be solidified is deformed along the surface 61, and the central portion thereof protrudes toward the side opposite to the film forming substrate 40a side.

  Subsequently, the layer 15a to be solidified is immersed in the coagulation bath 70 in which the coagulation liquid LQ is stored to be coagulated. At this time, as shown in FIG. 7, the film forming substrate 40a integrated with the die 60 has an outer peripheral portion substantially parallel to the liquid surface of the coagulating liquid LQ and coagulating the surface of the layer 15a to be coagulated. The liquid LQ faces the liquid surface. While maintaining this state, the film formation substrate 40a is slowly lowered, and the layer 15a to be solidified is immersed in the coagulation liquid LQ.

  Since the central portion of the layer to be solidified 15a protrudes downward, the surface of the layer to be solidified 15a first comes into contact with the solidified liquid LQ at the center of the circle when viewed from above. Thereafter, as the film forming substrate 40a descends, the position of the surface of the solidified layer 15a that is in contact with the solidified liquid LQ moves while expanding in a circle from the center of the solidified layer 15a toward the outer periphery. To do. That is, it moves along the radial direction of the layer to be solidified 15a with time.

  At this time, in the surface of the solidified layer 15a, the portion near and above the liquid surface of the coagulating liquid LQ is a part that will come into contact with the coagulating liquid LQ as the film forming substrate 40a descends. In the portion, the aggregation of the resin starts to proceed toward the contact portion with the coagulation liquid LQ, that is, toward the center of the layer to be solidified 15a. Thereafter, as the film forming substrate 40a is further lowered, the portion comes into contact with the coagulating liquid LQ. As a result, in the portion of the solidified layer 15a that has passed the liquid level of the solidified liquid LQ, the bubbles 10a are formed so as to extend from the film forming substrate 40a side toward the surface of the solidified layer 15a. ing. In addition, each of the bubbles 10a is in a state where the surface side portion is inclined along the direction toward the center of the film forming substrate 40a. That is, the inclined portion 12a as described with reference to FIG. 5 is formed.

  When the entire layer to be solidified 15a is immersed in the coagulating liquid LQ, the lowering of the film forming substrate 40 is stopped. At this time, the bubbles 10a as described above are formed in the entire layer to be solidified 15a and are in the state shown in FIG.

  As a result, in the elastic resin sheet 2a formed through such a solidification step, the first angles in all the bubbles 10a are all about 90 degrees as described with reference to FIG.

  For reference, the configuration of a polishing pad 1b according to a comparative example of the present invention will be described with reference to FIG. FIG. 8 is a diagram showing the arrangement of the bubbles 10b formed in the elastic resin sheet 2b of the polishing pad 1b. As shown in FIG. 8, the polishing pad 1b is different from the polishing pad 1 only in the arrangement of the bubbles 10b formed in the elastic resin sheet 2b, and is otherwise the same as the polishing pad 1. In the following description, only the difference will be described, and detailed description of points common to the polishing pad 1 will be omitted. In the following description, a portion of the polishing pad 1b corresponding to the configuration of the polishing pad 1 (for example, the pad base material 20) is denoted by a letter “b” such as “pad base material 20b”.

  Each of the bubbles 10b includes a large-diameter portion 11b formed to have a relatively large diameter at the pad base material 20b side (supported surface Sfb side), and an inclined portion 12b extending from the large-diameter portion 11b to the polishing surface Spb. And have. The extending direction of the inclined portion 12b is not perpendicular to the polishing surface Spb but is inclined to the polishing surface Spb. This is the same as the bubble 10 of the polishing pad 1.

  On the other hand, as shown in FIG. 8, when the elastic resin sheet 2b is viewed along a direction perpendicular to the polishing surface Spb, the respective inclined portions 12b extend in the direction toward the polishing surface Spb (arrows in FIG. 8). The direction indicated by AR6 is all the same direction (downward in FIG. 8). The elastic resin sheet 2b in which the bubbles 10b are arranged in this way is obtained by applying the film forming substrate 40b on which the resin solution is applied (the solidified layer 15b is formed) to the coagulation bath 70 in the coagulation step of the wet film formation method. It can be formed by slowly descending and dipping while maintaining a state perpendicular to the horizontal liquid level of the coagulating liquid LQ stored in the liquid.

  As is apparent from FIG. 8, in the elastic resin sheet 2b, the direction in which each inclined portion 12b extends toward the polishing surface Spb and the circumferential direction of the elastic resin sheet 2b at the position of the inclined portion 12b (FIG. 8). The angle (first angle) formed with the direction indicated by the arrow AR7 is different for each bubble 10b.

  Therefore, when performing the polishing process, the time difference between the timing at which the object to be polished is pressed and the volume of the bubble 10b starts to decrease and the timing at which the opening 13b is blocked by the object to be polished is different for each bubble 10b. It will be different. As a result, the function of storing and discharging the slurry is not evenly exhibited in each bubble 10b. That is, in the polishing pad 1b according to this comparative example, polishing unevenness may occur.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

DESCRIPTION OF SYMBOLS 1, 1a: Polishing pad 2, 2a: Elastic resin sheet 10, 10a: Bubble 11, 11a: Large diameter part 12, 12a: Inclined part 13, 13a: Opening 15, 15a: Coagulated layer 20, 20a: Pad base material 30: Double-sided tape 40, 40a: Film-forming substrate 41a: Back surface 50: Coagulating liquid supply device 51: Slit 60: Stamping die 61: Surface 70: Coagulating bath LQ: Coagulating liquid Sf, Sfa: Supported surface Sp, Spa: Polishing surface

Claims (4)

A polishing pad having a polishing surface as a surface on one side of an elastic resin sheet that forms a circle in plan view, and a supported surface as a surface on the other side,
A plurality of elongated bubbles extending from the supported surface toward the polishing surface are formed inside the elastic resin sheet,
Each of the bubbles, a large diameter portion, the direction from the large-diameter portion on the polished surface, and at least in the vicinity of the polishing surface, said extending so as to be inclined with respect to the polishing surface elongated inclined portion And
When viewed along a direction perpendicular to the polishing surface, when the angle formed by the direction in which the inclined portion extends and the circumferential direction of the elastic resin sheet at the position of the inclined portion is a first angle, All of the bubbles are formed so that the first angles are substantially the same as each other. A method of forming a polishing pad having a surface on one side of an elastic resin sheet that is circular in plan view as a polishing surface and a surface on the other side as a supported surface,
A preparation step of preparing a resin solution in which a resin is dissolved;
An application step of forming a solidified layer by applying the resin solution to one surface of a film-forming substrate that is circular in plan view;
A solidification step of bringing a solidified liquid into contact with the surface of the solidified layer and solidifying the solidified layer;
In the solidification step, the position of the surface of the layer to be solidified that is in contact with the solidification liquid moves along the radial direction or the circumferential direction of the layer to be solidified over time. Pad formation method.   3. The formation of a polishing pad according to claim 2, wherein in the coagulation step, the coagulation liquid is brought into contact with a part of the surface of the layer to be coagulated while rotating the film forming substrate. Method. In the solidification step, the layer to be solidified is opposed to the liquid surface of the coagulation liquid, and the film-forming substrate is deformed so that a central portion of the layer to be solidified protrudes.
The method for forming a polishing pad according to claim 2, wherein the solidified layer is immersed in the coagulating liquid from the central portion.

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